Method for determining properties of an EUV source

Abstract

The disclosure provides a method for determining at least one property of an EUV source in a projection exposure apparatus for semiconductor lithography, wherein the property is determined on the basis of the electromagnetic radiation emanating from the EUV source, and wherein a thermal load for a component of the projection exposure apparatus is determined and the property is deduced on the basis of the thermal load determined.

What is claimed is: 
     
       1. A method for determining a contamination of a collector mirror of an EUV source of a semiconductor lithography projection exposure apparatus, the method comprising:
 determining, based on a change in geometry of a facet mirror of an illumination system of the projection exposure apparatus, a thermal load for the facet mirror due to EUV radiation emanating from the EUV source; and 
 determining the contamination of the collector mirror based on the determined thermal load for the facet mirror. 
 
     
     
       2. The method of  claim 1 , further comprising:
 determining a spatial distribution of the thermal load across a surface of the facet mirror due to the EUV radiation emanating from the EUV source; and 
 determining a distribution of the contamination of the collector mirror based on the determined spatial distribution of the thermal load across the surface of the facet mirror. 
 
     
     
       3. The method of  claim 2 , wherein the facet mirror comprises a field facet mirror. 
     
     
       4. The method of  claim 3 , wherein:
 the projection exposure apparatus further comprises a position sensor and a sensor target; and 
 the method further comprises determining the change in geometry of the field facet mirror based on a change in a distance between a position sensor and a sensor target. 
 
     
     
       5. The method of  claim 4 , further comprising using the projection exposure apparatus in a production operation while determining the thermal load for the field facet mirror due to EUV radiation emanating from the EUV source and determining the contamination of the collector mirror. 
     
     
       6. The method of  claim 3 , further comprising using the projection exposure apparatus in a production operation while determining the thermal load for the field facet mirror due to EUV radiation emanating from the EUV source and determining the contamination of the collector mirror. 
     
     
       7. The method of  claim 1 , wherein:
 the projection exposure apparatus further comprises a position sensor and a sensor target; and 
 the method further comprises determining the change in geometry of the facet mirror based on a change in a distance between a position sensor and a sensor target. 
 
     
     
       8. The method of  claim 7 , wherein the sensor target is supported by a plunger of a facet of the facet mirror. 
     
     
       9. The method of  claim 7 , wherein the facet mirror comprises a field facet mirror. 
     
     
       10. The method of  claim 1 , wherein the facet mirror comprises a field facet mirror. 
     
     
       11. The method of  claim 1 , further comprising using the projection exposure apparatus in a production operation while determining the thermal load for the facet mirror due to EUV radiation emanating from the EUV source and determining the contamination of the collector mirror. 
     
     
       12. The method of  claim 11 , wherein the facet mirror comprises a field facet mirror. 
     
     
       13. A method for determining a contamination of a component an EUV source of a semiconductor lithography projection exposure apparatus, the method comprising:
 determining, based on a change in geometry of a component of an illumination system of the projection exposure apparatus, a thermal load for the component of the illumination system due to EUV radiation emanating from the EUV source; and 
 determining the contamination of the component of the EUV source based on the determined thermal load for the component of the illumination system. 
 
     
     
       14. The method of  claim 13 , wherein the component of the EUV source comprises a collector mirror. 
     
     
       15. The method of  claim 13 , wherein the component of the illumination system comprises a facet mirror. 
     
     
       16. The method of  claim 13 , wherein the component of the illumination system comprises a field facet mirror. 
     
     
       17. The method of  claim 13 , further comprising:
 determining a spatial distribution of the thermal load across a surface of the component of the illumination system due to the EUV radiation emanating from the EUV source; and 
 determining a distribution of the contamination of the component of the EUV source based on the determined spatial distribution of the thermal load across the surface of the component of the illumination system. 
 
     
     
       18. The method of  claim 13 , wherein:
 the projection exposure apparatus further comprises a position sensor and a sensor target; and 
 the method further comprises determining the change in geometry of the component of the illumination system based on a change in a distance between a position sensor and a sensor target. 
 
     
     
       19. The method of  claim 18 , wherein the sensor target is supported by a plunger of a facet of the facet mirror. 
     
     
       20. The method of  claim 13 , further comprising using the projection exposure apparatus in a production operation while determining the thermal load for the component of the illumination system due to EUV radiation emanating from the EUV source and determining the contamination of the component of the EUV source.